Studies will continue on the composition, structure and function of neurofilaments. Homology between mammalian neurofilaments has been shown by immunological and peptide mapping procedures and more detailed studies will be undertaken on calf, dog and human neurofilaments. These studies will include the isolation of selected cyanogen bromide peptides from the proteins and their sequencing. At the same time the determination of the complete sequence of the calf neurofilament will begin. The development of a radioimmunoassay to assess the homology and to quantify neurofilaments in tissue extracts will continue. The problem is made difficult by the inclusion of sodium dodecyl sulfate need to solubilize the neurofilament protein; but the methodology of antibody adsorption to polystyrene spheres or the use of other procedures will be explored. The differentiation of glial and neurofilament proteins will be investigated by selective isolation from appropriate nerves and from glial cultures. Studies will also be made at the electron microscope level utilizing ferritin- or horseradish peroxidase- labeled anti-neurofilament rabbit globulin. Studies on the abnormal neurofilaments produced in the cat brain under the administration of aluminium chloride will be continued utilizing immunological and, if possible, microfingerprinting techniques. BIBLIOGRAPHICREFERENCES: Davison, Peter F. Neuronal Fibrillar Proteins and Axoplasmic Transport Brain Research 100 (1975) 73-80. Hong, B. S. and P. F. Davison. Characterization of Mammalian Neurofilament Proteins. Federation Proceedings 37;7 (1976) 1766.